We have previously shown that human leukocyte interferon (HuIFna) is biologically, antigenically and structurally related to adrenocorticotropic hormone (ACTH) and endorphins. Highly purified leukocyte interferon was composed of both 23,000 (23K) and 18,500 (18.5) dalton species. The 23K form can apparently be broken down into the 18.5 interferon and a 4.5K molecule which is identifiable as ACTH. Endorphin activity was associated with both the 23K and 18.5K forms. We propose using biochemical, biological and physiological methods to study: (1) the chemical nature of the ACTH-endorphin-leukocyte interferon linkage; (2) possible biological differences between leukocyte interferon and other lymphocyte products (lymphokines) in a putative regulatory circuit between the immune and neuroendrocrine systems. Long term objectives are to apply knowledge of the interferonneuroendocrine hormone relationship for possible purification and immunodetection of interferon, detection of certin neoplastic, immune, and infectious diseases and understanding of their pathophysiology. These studies may demonstrate an important link between virology, immunology and neuroendocrinology, which could eventually be exploited in the detection, prophylaxis and therapy of human diseases.